Problem: Gabriela starts counting at 31, and she counts by fives. If 31 is the 1st number that Gabriela counts. what is the 13th number that she counts?
Answer: What is the first number that she counts? $31$ What is the second number that she counts? $\begin{align*}&31 + 5 \\ &= 36\end{align*}$ What is the third number that she counts? $\begin{align*}&31 + 5 + 5 \\ &= 31 + (2 \times 5) \\ &= 41\end{align*}$ What is the 13th number that she counts? $\begin{align*}&31 + (12\times5) \\ &= 31 + 60 \\ &= 91\end{align*}$